Vacuum Brazing Machine

Vacuum brazing machine is used for vacuum brazing purpose. Vacuum brazing is a typical brazing process, which is used for joining different types of similar or dissimilar metals. The bonds formed are high quality and superior compared to the bonds created by other brazing processes. Vacuum brazing is done in a container or chamber under reduced pressure. The chamber or the container is called vacuum furnace. This process is also known as furnace brazing conducted in a vacuum atmosphere.



Vacuum Brazing
Vacuum brazing is one of the most efficient methods of metal bonding. It is a special type of furnace brazing. The bonds created by this process are very strong. It provides a hermetically sealed, diffusion bonded joint area for machined, cast, formed and stamped parts and tubing. After the vacuum brazing, the assemblies remain clean and bright.

The process is performed inside a vacuum chamber where the atmospheric pressure is quite low. Due to the reduced atmospheric pressure the chances of oxidization become very less. The furnaces are classified as hot wall or cold wall on the basis of the location or positioning of heating and insulating components. Commonly cold wall furnaces are preferred in vacuum brazing.

Uses & Applications
Since the atmospheric pressure inside the chamber is very low so the metals to be joined have no threats of further oxidization. So the base metals are promptly wet by the filler materials. It facilitates the bonding process and creates very strong bonds. The need of flux is reduced and the bonds are superior in strength, cleanliness. They found a lot of applications in different sectors. They are mainly used for oxidation sensitive applications. Some of its common applications are :

• Brazing super alloys
• Brazing base metals of stainless steel
• Brazing oxidation sensitive materials in aerospace industry
• Brazing carbon low alloy steels
• Thermal engineering
• Ceramics industry

Vacuum Furnace
Vacuum furnace is a type of furnace used for heating different types of materials specially metals to very high temperatures. It is used for carrying out brazing, sintering and other heat treatments with high consistency and low contamination.



In a vacuum furnace the product in the furnace is surrounded by a vacuum. The absence of air or other gas prevents heat transfer with the product through convection and removes a source of contamination.

Benefits of Vacuum Furnace

• Vacuum furnaces provide uniform temperatures in the range 2000–2800°F (1100–1500°C).
• The contamination of the products by carbon, oxygen and other gases are reduced.
• It provides quick cooling of products.
• The process can be computer controlled to ensure metallurgical repeatability.
• Temperature can be controlled within a small area.

In vacuum furnaces the heat-treating process takes place inside an airtight vessel, where a vacuum is created. This helps to alleviate surface reactions. Furnaces are built of several kinds of high temperature (refractory) materials to hold the process material and hold in the heat without breaking down during the several months that they usually run.

Specifications
Before choosing a vacuum furnace you should consider some important points.

• Process Temperature: It is the maximum temperature at which the unit may operate and still maintain rated functioning.
  
  
• Width: It refers to the internal width dimension of the unit. But for tube furnaces, it is the outer diameter of the tube.
  
  
• Height: It is the internal height dimension of the furnace.
  
  
• Length: It is the length dimension of the unit and for tube furnaces, the heated length.
  
  

Heat Sources for Vacuum Furnaces
Different sources of heat can be used for heating the furnace. The choice for heat source include:

• Arc Combustion
• Electrical or Resistance Conduction
• Induction
• Infrared
• Microwave
• Dielectric
• Steam
• Natural Gas/ Propane/ Oil/ Other Fuel